Skip to content

Roof Pitch Calculator

Our roof pitch calculator uses Google Street View with a simple overlay to allow you to determine your roof pitch. Simply enter your address and line your roof line with the bar that matches your roof edge. This is a simple tool that eliminates the need to get on the roof to measure your home’s roof pitch manually.

Home with a roof pitch of 4/12 or 18.43 degrees.

Why Does Roof Pitch Matter?

Understanding the importance of roof pitch allows homeowners, architects, and contractors to make informed decisions about roofing design, material selection, and maintenance. The optimal roof pitch depends on various factors, including climate, architectural style, and specific functional requirements for the building. It can affect things like water runoff and drainage, snow load capacity, attic space, and durability concerns. The pitch of your roof isn’t just an aesthetic feature, it really matters! Our roof pitch calculator lets you know ahead of time how your pitch can impact your roofing project. 

Once you get your roof pitch sorted, hop over to our custom roofing material calculators below and see what your roofing estimate could look like within seconds!

7 Reasons Why Roof Pitch Matters

1. Climate Compatibility

The slope of a roof can significantly impact how effectively it deals with weather conditions. For example, in areas with high snowfall, a steeper pitch is often recommended to allow the snow to slide off the roof rather than accumulate and cause potential structural damage. On the other hand, in wind-prone areas, a lower pitch might be advantageous to reduce wind resistance.

2. Water Drainage

A roof with the right pitch will allow rainwater to drain off effectively, reducing the risk of water pooling and potential leaks or water damage. Proper drainage means you’ll have less issues down the road that can compromise building structure and integrity. 

3. Structural Integrity

The pitch of a roof can affect the structural load bearing of a building. Roofs with steeper pitches can sometimes support heavier loads than those with lower pitches. These factors are important especially in areas with high snowfall, as steeper pitches help prevent the accumulation of snow to reduce the risk of structural stress being caused by piling up snow. 

4. Architectural Style

The pitch of a roof greatly contributes to the overall aesthetic and architectural style of a building. Certain styles, such as Victorian or Gothic, demand specific roof pitches to maintain the visual impact and aesthetic of those styles. The roof pitch becomes a key element in many of these structures! 

5. Usable Space

The pitch of a roof can impact the amount of usable space in the upper areas of a building. For example, a higher pitched roof could allow for an attic or loft space as it creates more area for headspace and usable areas. For homeowners looking for more versatile space, taller pitches are much more attractive. 

6. Energy Efficiency

Roof pitch can influence the amount of sun exposure the roof gets, which in turn affects the heating and cooling dynamics of the building. This can have a big impact on energy efficiency and costs. For instance, in cooler climates like Vermont, a steeper roof optimizes sunlight capture and can keep homes warmer. Warmer climates are more likely to have lower pitches or even flat roofs (think Arizona) that provide better shading to reduce cooling costs. 

7. Installation of Rooftop Equipment

If you’re planning to install equipment on your roof, like solar panels or satellite dishes, the roof pitch could influence the efficiency and installation process of these items.The pitch influences these installations, as it can impact the angle and orientation of the equipment for optimal performance. The ease of installation and the overall effectiveness of rooftop equipment are closely tied to the roof’s pitch.

Roof Slope Multiplier: A Useful Tool

A Roof Slope Multiplier, often referred to as a Roof Pitch Factor, is a number that, when multiplied by the plan area (the projection of the roof onto a flat plane), gives the actual surface area of the roof. It accounts for the increased area that a pitched or sloped roof has compared to a flat one.

In other words, the roof slope multiplier adjusts the horizontal “footprint” of the house to match the true surface area of the sloped roof. This is important when calculating materials needed for roofing, as the sloped surface area will be larger than the plan area.

The math behind calculating the roof slope multiplier involves trigonometry. If you have a roof pitch given as “rise over run” (like 4/12, 6/12, etc.), the multiplier can be calculated as the square root of ((rise/run)^2 + 1).

So, for example, if you have a 6/12 roof pitch, the roof slope multiplier is the square root of ((6/12)^2 + 1), which equals about 1.12. This means the actual surface area of the roof is about 12% larger than the plan area due to the slope.

Simple Roof Slope Multiplier Table

We provide a basic table to give you an idea of common roof slope multipliers based on pitch. The exact multiplier can vary slightly based on the exact slope of the roof:

Roof PitchSlope Multiplier
Simple Roof Slope Multiplier Table

Please note that the roof slope multiplier, also known as a roof pitch factor, is a number that, when multiplied by the flat area covered by a sloped roof, gives the actual area of the roof.

The pitch factor is derived from the square root of ((rise/run)² + 1). These factors are extremely helpful when estimating the amount of roofing material required.

Keep in mind these are approximations and for a more accurate result, you might want to calculate based on the exact slope of your roof.

How Can I Measure My Roof Size?

Measuring your roof size can be achieved in a few simple steps, but keep in mind that safety should always be your top priority when doing any kind of work involving heights. Here’s a step-by-step guide:

1. Safety First

Always use a sturdy ladder, and it is recommended to have someone hold the ladder for you. Wear non-slip shoes and use a safety harness if possible. The CDC states that 97% of all roofing and ladder accidents happen at home. Do not skip on the safety precautions! 

2. Measure the Width and Length of the Building

This can typically be done on the ground. Measure the width and length of your home, remembering to include any overhangs or extensions of the roof.

3. Determine the Pitch of the Roof

Here is a full guide on “How to calculate roof pitch?”, but here is a quick summary. Roof pitch is the steepness of a roof and is expressed in the inches a roof rises vertically for every 12 inches it extends horizontally. The pitch is used to establish the roof’s multiplier which adjusts for the extra width that a pitched roof has compared to a flat one. 

4. Calculate the Total Square Footage

Multiply the length times the width of the building, and then multiply this by the pitch multiplier. For example, if your building is 30 feet wide, 50 feet long and has a 6/12 pitch, the total square footage of your roof would be 30 * 50 * 1.118 = 1,677 square feet.

5. Factor in Roof Features

If your roof has gables, dormers, or other features, you’ll need to calculate these areas separately and add them to the total.

6. Use AI to Measure Your Roof

We’ve created a simple tool to measure your roof and provide you with an exact estimate, plus it will find a roofer in your local area. If you’re in the market for a new roof we recommend using our roof replacement cost calculator or our new roofing calculator to measure your roof and get a rough ballpark estimate on your roof replacement costs.
Read more tips on our blog, “How to measure a roof for shingles?

Roof Pitch FAQ

What is the best roof slope for snow?

For snow-prone locales, a roof gradient of about 30°, akin to a 6/12 or 7/12 pitch, is optimal. The effectiveness of snow sliding off your roof can be influenced by factors such as the roofing material, snow direction, and wind flow.

What is the steepest roof pitch?

A 12/12 roof gradient is often called a “45-degree roof” because it forms a 45-degree angle with the horizontal. This pitch indicates that the roof rises 12 inches for every 12 inches of run, forming a perfect diagonal or 45-degree angle. This is the steepest standard pitch for a roof.

In terms of the Roof Slope Multiplier, a 12/12 roof pitch has a multiplier of approximately 1.414 (calculated as the square root of ((12/12)^2 + 1)). This means the actual surface area of a 12/12 pitched roof is about 41.4% larger than the plan area. This factor is critical when estimating the amount of roofing materials needed.

Due to its steepness, a 12/12 pitch roof can effectively shed water and snow, making it an ideal choice in regions with heavy precipitation. However, its steep incline also means working on such a roof can be more dangerous, requiring safety equipment and potentially professional help.

What is the minimum slope for a roof?

The tiniest roof slope is 0.5/12. Be cautious with flat roofs, as they may accumulate water or snow, posing a risk of roof collapse. For flat roofs, EPDM rubber is a recommendable choice due to its durability, water resistance, and eco-friendliness.

What slope of a roof is walkable?

Roof slopes of 6/12 (26.5°) or lower are generally deemed walkable without additional safety measures. For slopes between 8/12 and 10/12 (33°-40°), extreme care is advised. Steeper roofs necessitate specific gear or scaffolding.

Can a 3/12 pitch roof be shingled?

Yes, a 3/12 pitch roof can be shingled. But remember to use a waterproof membrane underneath the shingles to avoid future leaks. Ensure to adhere to the manufacturer’s guidelines when installing shingles on low-slope roofs.

What is a 30 degree roof pitch?

A roof slope of 30° roughly corresponds to a 7/12 pitch. To transition from degrees to pitch ratio, apply the tangent of the angle and multiply the outcome by 12.

What is a 4/12 roof slope?

When we talk about a 4/12 roof gradient, it signifies that for every 12 horizontal inches, the roof elevates by 4 inches. This slight slope creates an angle of 18.5°. Ideal for water drainage, but not designed to withstand heavy snow loads. For a roof of this pitch, consider using standard asphalt or composition shingles.

What is an optimal roof slope?

The optimal roof slope varies with your design preferences. For a contemporary style, a nearly flat roof with a pitch of 1:40 is desirable. For Gothic aesthetics, the rafters should match the span. An Elizabethan style demands longer rafters. If snowfall is frequent in your region, aim for a slope of at least 10/12 (40°). For high wind conditions, a slope between 4/12-6/12 (18.5°-26.5°) is advised.

Limitations Of Our Roof Pitch Calculator

Since our interactive calculator requires the use of Google Street View there are some limitations. This is because of privacy concerns and limited access to homes via Google Street View.

Blurry Homes

If you find that a home is blurred it means that a homeowner has requested Google blur their home for privacy concerns. We have no ability to display this home as our free roof pitch calculator requires Google Street View. 

A home blurred on Google Street View for privacy.

My Home Doesn’t Appear When I Enter The Address

Not all homes are included in Google Street View. Some homes are outside of their coverage area or are not viewable because of inability to access. Meaning a home might be in a gated community and therefore not visible on Google Street View. Our app will only load addresses and homes available to Google Street View.

How Can I Use This Tool On My Cellphone?

To use our tool on your cellphone you must rotate it to a landscape view. Our roof pitch calculator works best on a tablet or desktop computer. We’re working on new technology everyday to make free roofing tools available to the public. 

I See Different Pitches At An Angle

The best use of our tool is to look straight at your home. If you’re at an odd angle you will get a different pitch. Always try to look at the home as if you’re standing out front directly looking at it. 

Good Example Use:

A Good Roof Pitch Measurement directly facing the home.

Bad Example Use: